Department Drug Discovery and Development, Bee-Biomedicals Inc., St. Catharines, ON L2S 3A1, Canada.
Department of Biochemistry, McMaster University, Hamilton, ON L8S 4L8, Canada.
Molecules. 2018 Nov 23;23(12):3067. doi: 10.3390/molecules23123067.
Honey is composed of macromolecules arranged into multicomponent colloidal particles dispersed in a supersaturated sugar solution. The core part of colloidal particles in honey is made up of high-molecular weight protein-polyphenol complexes. We designed a multi-step extraction process to gain better insight into the phenolic compounds strongly bound to proteins in honey. Honeys were sequentially extracted by solvents of reduced polarities and the extraction process was monitored by LC-ESI-MS/MS. Unexpectedly, the results revealed ubiquinone-like compounds that partitioned to both, soluble supernatants and protein-bound insoluble residues from which they were released after the pronase-digestion of proteins. The accurate mass measurement and MS/MS fragmentation patterns using UPHLC-MS/MS coupled to quadrupole orbitrap confirmed their identification as ubiquinones. Distribution of ubiquinone-bound proteins was further investigated by the fractionation of honey protein-polyphenol complexes by size-exclusion chromatography followed by LC-ESI-MS analysis. Mass spectra revealed the presence of ubiquinones (UQs) in fractions of high polyphenol to protein ratio. The dominant mass peaks observed in these fractions were identified as UQ-3, UQ-5, and UQ-7. Since the quinone group of UQs is involved in redox reaction, we discuss the possibility that UQs may contribute to the antioxidant/proxidant activity of these complexes.
蜂蜜由大分子排列成多组分胶体颗粒分散在过饱和糖溶液中组成。胶体颗粒的核心部分由高分子量蛋白质-多酚复合物组成。我们设计了一个多步提取过程，以更深入地了解与蜂蜜中蛋白质结合紧密的酚类化合物。蜂蜜依次用极性降低的溶剂提取，并用 LC-ESI-MS/MS 监测提取过程。出乎意料的是，结果显示了类泛醌化合物，它们分配到可溶性上清液和蛋白质结合的不溶性残留物中，在用蛋白酶消化蛋白质后，它们从后者中释放出来。使用 UPHLC-MS/MS 与四极杆轨道阱联用进行精确质量测量和 MS/MS 碎片模式分析，证实了它们为泛醌的鉴定。通过大小排阻色谱法对蜂蜜蛋白质-多酚复合物进行分级，然后进行 LC-ESI-MS 分析，进一步研究了类泛醌结合蛋白的分布。质谱显示，在高多酚与蛋白质比值的分数中存在泛醌（UQ）。在这些分数中观察到的主要质量峰被鉴定为 UQ-3、UQ-5 和 UQ-7。由于 UQs 的醌基团参与氧化还原反应，我们讨论了 UQs 可能对这些复合物的抗氧化/促氧化剂活性的贡献。
